1. Field of the Invention
The invention relates generally to fire control systems for controlling and aiming weapons. More particularly, the invention relates to fire control systems for controlling and aiming mortars.
2. Description of the Prior Art
Prior art mortar fire control systems are generally manual operator-controlled systems usually consisting of a simple telescopic sight mounted adjacent a mortar barrel and utilized in conjunction with two (sometimes one) aiming stakes set at approximately 50 meters and 100 meters from the telescopic sight and at a certain predetermined angle from the forward direction of the mortar. Elevation and azimuth angular orientations of the mortar barrel relative to the aiming stakes are determined by observation of elevation and azimuth angular scales which show the respective elevation and azimuth positions of the telescopic sight relative to some predetermined orientation.
In certain prior art applications the aiming stakes are equipped with light reflectors for reflecting a continuous light beam from the telescopic sight. Generally these auxiliary light reflectors are utilized at night and differentiate the aiming stakes by, for example, reflecting red light from the first aiming stake and reflecting green light from the second or far aiming stake.
The prior art procedure for controlling the fire of a mortar is based essentially upon the use of the aforementioned aiming stakes. The gunner, or person operating the mortar, is generally able to aim the mortar at any target by varying the azimuth and elevation orientations of the mortar barrel relative to predetermined referenced azimuth and elevation angles established by the position of the aiming stakes relative to the mortar.
The prior art aiming procedure is generally as follows:
Once the mortar is placed in a desired location and leveled, two aiming stakes are placed on a straight line running from the mortar position in a convenient direction. These aiming stakes are usually placed at approximately 50 meters and 100 meters respectively. In any event, the far aiming stakes should be approximately twice as far from the mortar as the near aiming stake.
After the mortar and the aiming stakes are placed, it is necessary to "refer" the telescopic sight. This is generally done by aligning the sight with the two aiming stakes without disturbing the lay of the mortar. A procedure for referring the sight may differ slightly depending upon the particular mortar telescopic sight which is used although, in general, the concept of referring the sight to establish a reference line for aiming the mortar is almost always followed. However, the initial angular orientation on the telescopic sight may vary depending upon the type of sight used. The line of sight of the sight unit is generally aligned with the straight line formed by the aiming stakes which are generally not placed directly in front of the mortar since the line of sight to the stakes will be blocked by the barrel when the sight is turned to the right a predetermined amount (approximately 1,300 mils since the sight is generally mounted on the left side of the barrel). To reduce this limitation the aiming stakes are normally placed to the left front of the mortar.
Once the mortar sight is "referred" the mortar barrel position (angular and elevational) may be altered within a predetermined range in order to aim the mortar at targets relative to the reference angular and elevation orientations. Aiming outside this predetermined range requires re-setting the aiming stakes and repeating the "referring" of the telescopic sight.
Prior art mortar fire control systems are two dimensional systems which are not capable of 3-axis control of mortar fire since the telescopic sight used in conjunction with prior art mortars consists of a single axis telescope having a reticle using vertical and horizontal cross-hairs only. Thus, prior art mortar fire control systems are subject to a certain amount of aiming error because they are unable to sense the third dimension or cant angular orientation of the mortar barrel relative to a predetermined reference.
Moreover, prior art mortar fire control systems require the gunner to observe considerable care in setting up and aligning the aiming stakes through the telescopic sight. This necessarily delays the availability of the mortar for firing and prevents the gunner from rapidly changing or correcting the aiming reference line of the mortar in order to hit a target.
Accordingly, there exists a need for a mortar fire control system capable of efficiently and rapidly indicating the azimuth, elevation and cant angular orientations of a mortar barrel relative to predetermined reference values of these parameters.